Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$137.56	11.801%	$153.7935	$153.79	$153.80	$153.80
Purchase #2	$18.92	4.116%	$19.6987	$19.70	$19.70	$19.70
Purchase #3	$103.86	6.659%	$110.776	$110.78	$110.80	$110.80
Purchase #4	$112.53	11.533%	$125.5081	$125.51	$125.50	$125.50
Purchase #5	$51.82	3.245%	$53.5016	$53.50	$53.50	$53.50
Purchase #6	$222.59	9.838%	$244.4884	$244.49	$244.50	$244.50
Purchase #7	$173.61	13.161%	$196.4588	$196.46	$196.45	$196.50
7 purchase totals =	$820.89		$904.2251	$904.23	$904.25	$904.30